Snow traction unit



Oct. 23, A C. BECKER SNOW TRACTIQN UNIT Filed 000. '7, 1960 United States Patent O 3,059,711 SNW TRACTION UNIT Alvin C. Becker, Bellflower, Calif., assignor to himself and Catherine Becker, jointly Filed Oct. 7, 1960, Ser. No. 61,139 4 Claims. (Cl. 180-7) The present invention relates to a snow traction unit which utilizes an elongated, rotatably driven shaft, having la helical screw thread formed thereon, as the means for obtaining traction upon the surface of a body of snow.

One object of the invention is to provide a traction unit for driving or pulling a load either uphill or down upon the surface of a body of snow.

Another object of the invention is to provide a traction unit which is ideally suited for driving or pulling a load upon the surface of a body of snow, or upon an icy surface, and which may also be conveniently adapted as a water surface propulsion unit when fording streams.

A further object of the invention is to provide a snow traction unit which is capable of packing down the snow over which it traverses, to the extent necessary to secure good forward traction.

The above and other objects and advantages of the yinvention will be more readily appreciated from the following description in conjunction with the accompanying drawing, in which:

FIGURE l is a perspective view of my snow traction unit driving a snow sled, and also includes a side View showing its use by two skiers;

FIGURE 2 is a perspective View of my snow traction unit with the lid raised to show the motor location;

FIGURES` is a partially cross-sectional, plan View of the Working portion of my snow traction unit; and

FIGURE 4 is a Vertical cross-sectional view taken on the line 4-4 of FIGURE 3.

Reference is now made to the drawing which illustrates a presently preferred embodiment of the invention. A generally rectangular housing base A which is open on its under side supports a horizontally separated pair of impeller shafts B-l and B-2. Each of the impeller shafts is rotatably supported from its two ends by means of suitable bearings which are provided in the end walls of the housing base A. A gear-and-chain drive mechanism C carried in the forward end of the housing base A provides the means for driving the two impeller shafts concurrently. An upper housing D extends above the housing base A and carries a fully enclosed motor E. A bevel gear F is adapted to receive direct drive from the motor E and imparts same by means of drive mechanism C to the impeller shaft. On the exterior of the housing a suitable hitch G is provided for coupling the traction unit to a load.

Before giving further `consideration lto the complete structure of the apparatus `and its various applications, it will be advantageous to describe in some detail the structure and operation of the impeller shaft. The impeller shaft B-1 `will therefore be described in some detail.

impeller shaft B-1 is -made of metal and has relatively small diameter portions 10, 11 at its rearward and forward ends, respectively, by means of which the shaft is rotatably supported. A helical thread 15 is formed on the exterior of the shaft and extends throughout most of the length of the shaft, there being in the embodiment Ffce shown approximately 6 complete turns or revolutions of the thread 15 about the longitudinal axis of the shaft. At its forward end 16 the thread 15 is smoothly tapered radially inwardly toward the base of the shaft B-1, the purpose of this taper being to prevent serious damage to the impeller shaft when from time to time a foreign object such as a rock or branch is encountered in the body of snow upon which the traction unit is traveling.

The longitudinal separation between `adjacent turns of the thread 15 is substantial, and is in fact, comparable to the outside diameter of the thread measured transverse to the longitudinal axis of the shaft. It will be seen that the helical thread 15 defines a rather sharp cutting edge throughout its length. The rear edge surface 17 of the helical thread is not perpendicular to the longitudinal shaft axis, but instead is inclined at a substantial angle relative thereto, the purpose being to impart not only rearwardly but also downwardly thrust upon the snow lying beneath the shaft as the shaft rotates. In the particular illustration shown the taper of the rear edge surface of the thread is approximately 35 degrees measured with reference to a plane perpendicular to the longitudinal axis of the shaft. Alternatively, it may be stated that the taper of the rear edge surface of the thread is approximately 55 degrees measured relative to the longitudinal axis of the shaft.

Impeller shaft B-2 is in all respects identical to shaft B-l, except for the direction of progression of the helical thread. Thus it will be seen that the helical thread 15 of the shaft B-l progresses counter-clockwise from the rear end of the shaft to the forward end, when viewing the shaft from its rearward end 10. On the other hand, the thread 15 of shaft B-Z progresses clockwise when the shaft is viewed in the same manner. Y

Housing base A includes left and right vertical side walls 21, 22, and rearward and lforward vertical end walls 23, 24. A nose plate 25 lies forwardly of and parallel to ythe forward wall 24. An enclosed compartment 26 be- -tween the forward wall 24 and nose plate 25 is iilled with light oil in order to maintain continuous lubrication of the gear-and-chain mechanism C, now to be described.

A -toothed sprocket 31 is rigidly aliixed to the forward extremity 11 of impeller shaft B-l, and a similar toothed sprocket 32 is rigidly affixed to the forward extremity 11 of the shaft B-Z. Intermediate to the forward impeller shaft ends 11 and 11 a pair of auxiliary shafts 34, 35 are carried in vertically spaced positions by the end wall 24 and nose plate 25. A large gear wheel 35 and a small gear wheel 36 carried on the shaft 34 are rigidly fastened together, and a chain 37 provides a direct drive of the sprocket 31 from the gear wheel 36. A large gear wheel 38 and a small -gear Wheel 39 carried by shaft 35 are rigidly Iaffixed together, and a chain 40 provides a direct drive from gear wheel 39 to sprocket 32. Shaft 34 is an idler shaft, that is, the gear wheels 35 and 36 rotate freely upon it. Shaft 35 is the upper one of the two auxiliary shafts and has one end protruding into the housing base A, and lwhich carries a bevel gear F. The bevel gear F and the gears 38, 39 are rigidly affixed -to the shaft 35, which shaft rotates in suitable bearings 42, 43 provided on the end plate 25 and end Wall 24, respectively, hence lgear F provides a means for the direct coupling of the motor E to the impeller shafts B-1 and B-2.

It will be observed that the application of a rotating drive to the gear F produces rotation of the impeller shaft B-2 in the same direction. However, the gear wheels 35, 36 provide a reversal of the direction of drive for impeller shaft B-l, which therefore rotates with the same rate of rotation as shaft B-Z but in the opposite direction.

Motor E is directly coupled to the drive gear F by any suitable transmission mechanism. The lid 45 of upper housing D may be raised for access to the motor E, but during operation it is generally kept closed so as to completely protect the motor from the snow.

A hitch G is provided which includes a forwardly extending tongue 51 having a ball joint 52 on the front extremity thereof, a crossbar 53 across the rearward end of the tongue 51, and side members 54, 55 extending rearwardly from the two ends of the crossbar 53 The extremities of the side members 54, 55 are pivotally supported at 56, 57, respectively, from the side walls 21, 22, of the housing base A.

FIGURE 1 in the left-hand portion thereof illustrates a snow sled 6) which is being propelled in front of the traction unit of the present invention. Steering is accomplished by the sled itself, by means of conventional runner steering mechanism, and the traction unit simply imparts a forward thrust by means of the rigid hitch G and its forward ball member 52. A exible tube 61 extending between the snow sled 60 and upper housing D of the traction unit carries a cable for controlling the throttling action of the motor E, in order to control the speed at which the snow sled 60 will travel.

In the right-hand portion of FGURE 1 the snow traction unit of the present invention, designated as A-D, is illustrated in greatly reduced form. One skier 64 is shown as being pushed in front of the unit while another skier 65 is illustrated as being pulled behind it. As shown in both portions of FIGURE l, and also in FIG- URE 2, the helical threads 15, of the impeller shafts B-1 and B-Z protrude a substantial distance below the side walls of the housing base A.

In operation a certain amount of loose snow will tend to move up inside the housing base A and to ocupy the space between the two impeller shafts B-1 and B-2, as well as the spaces on the outer sides of the two shafts. Also, loose snow may be thrown up above the impeller shafts. However, the success in obtaining traction depends upon the body of snow which lies underneath the traction unit. It is very significant that the rear edge surfaces 17, 17 of the impeller shaft threads are inclined or tapered at an angle. The significance of this is that the snow lying underneath the impeller shafts, and upon which the weight of the impeller shafts rests, is not simply thrust rearwardly, but is also given a considerable component of downward thrust at the same time. This action is progressive, from front to rear of the impeller shafts, with the result that the rear end of the traction unit tends to ride deeper in the snow than does the forward end. Thus, with a taper of the rear edge surface of the thread of approximately degrees, and a tilting of the entire housing of the traction unit of 10 degrees, the direction of thrust imparted to the snow underneath the impeller shafts is rearwardly and 45 degrees downwardly.

It will be seen from the drawing that each of the impeller shafts B1 and B-2 has its rearward end ensmalled to the same extent as its forward end. Furthermore, on each impeller shaft the forward edge surfaces of the helical thread are inclined or tapered at the same angle as the `rearward edge surfaces. One result of this arrangement is that the vehicle may be driven backwards as well as forwards. Another result of this arrangement is that the impeller shafts are interchangeable simply by rotating them end for end, hence in the manufacturing operation only a single standard part is manufactured for this purpose.

The friction between the impeller shaft and the snow, when the shaft rotates, tends to impart a sideward motion to the impeller shaft. However, with the arrangement as presently illustrated, wherein a pair of otherwise identical impeller shafts have helical threads which progress in opposing directions, and the two impeller shafts are also rotated in opposing directions, these side thrust forces are effectively cancelled out. The net result is a driving force which is directed forwardly, and also upwardly at an angle of about 35 degrees to 45 degrees, which thus insures the continued compacting of the snow so as to provide the necessary traction forces.

While the impeller shafts B-l and B-Z are laterally separated, and such separation is necessary, the amount thereof does not appear to be critical. It fact it is quite feasible to incorporate the two impeller shafts into a snow sled to serve as its rear runners. A clutch mechanism may be used if desired to control separately the rates of rotation of the two impeller shafts, so as to impart a guiding motion either to the left or to the right as may be desired.

The invention has been described in considerable detail in order to comply with the patent laws by providing a full public disclosure of at least one of its forms. However, such detailed description is not intended in any way to limit the broad features or principles of the invention, or the scope of patent monopoly to be granted.

What I claim is:

l. An impeller shaft for a snow traction unit comprising, in combination:

an elongated, straight metal base portion having tapered ends;

and a helical thread formed integral with said base portion and extending longitudinally between said tapered ends thereof;

said helical thread throughout its length having a longitudinal forward edge surface which is inclined at an angle of approximately degrees relative to the longitudinal axis of the shaft, and a longitudinal rearward edge surface which is inclined at an angle at approximately 55 degrees relative to the longitudinal axis of the shaft, said forward and rearward edge surfaces converging to define a sharp cutting edge;

said helical thread being of substantially constant outer diameter throughout the main portion of its length but being smoothly tapered radially inwardly at each end thereof;

said impeller shaft being adapted for driving the aS- sociated snow traction unit in either a forward or reverse direction, the driving edge surface of the thread then exerting a rearwardly and simultaneously downwardly pressure upon the snow lying beneath the shaft as the shaft rotates.

2. A snow traction unit comprising, in combination:

an identical pair of metal impeller shafts each including a straight, elongated base portion having tapered ends, and a helical thread formed integrally with said base portion and extending longitudinally between said tapered ends thereof, said helical thread having a substantially triangular radial cross-sectional configuration defining a sharp outer cutting edge:

a housing upon which said impeller shafts are carried in horizontally separated, parallel relationship, the two ends of each of said shafts being rotatably attached to said housing, said housing being adapted to extend above and be supported by said shafts when said shafts rest side by side upon the surface of a body of snow;

and drive means carried by said housing for rotatably .driving said shafts in opposing directions;

said shafts being attached to said housing in reversed end-for-end relationship such that the direction of progression of the helical thread on one is opposite to the direction of progression of the helical thread on the other;

said traction unit being adapted to travel in either a forward direction or a reverse direction along the longitudinal axes of said shafts, the driving edge sur faces of the helical threads exerting both a rearwardly and downwardly pressure upon the snow lying beneath the shafts as the shafts rotate.

3. A snow traction unit as claimed in claim 2, wherein said helical threads are smoothly tapered radially inwardly at each end of said shafts to the base portions thereof so as to avoid severe impacts upon striking a foreign object in the snow.

4. A snow traction unit as claimed in claim 2, wherein the tapered edge surfaces of said helical threads are dis- 1() posed at an angle of approximately 35 degrees relative to a plane Ilying perpendicular to the longitudinal axis of the associated impeller shaft.

References Cited in the iile of this patent UNITED STATES PATENTS Harvey Mar. 15,

Burch Mar. 5,

Petersen Jan. 2,

Burch Oct. 10,

Wels I an. 27,

FOREIGN PATENTS Great Britain Apr. 9, 

